1. Field of the Invention
The present invention is directed to methods of synthesizing fluorosulfonylamide, FSO2NH2, and salts of the fluorosulfonylamide anion, −[FSO2NH]−.
2. Background
It is known that slow addition of SO2F2 to NH3 (or vice versa) produces SO2(NH2)2 (sulfamide) and oligomers thereof. See, e.g., U.S. Pat. No. 3,411,889 (“Kopec”) and U.S. Patent Application Publication No. 2012/0020867 A1 (“Morinaka”). For example, in Comparative Example 1, Morinaka shows that SO2F2 added to a 3.2 molar excess of NH3 in acetonitrile at 5° C., followed by stirring at room temperature for 48 hours, filtration, and distillation of the solvent provided SO2(NH2)2 as a white powder. Analysis of the product showed that FSO2NH2 was produced as a minor (3%) impurity. In Comparative Example 2, Morinaka shows that slow addition of a 3.5 molar excess of NH3 to a solution of SO2Cl2 in acetonitrile provided SO2(NH2)2. Likewise, Kopec discloses that addition of SO2F2 to NH3 at −65° C. to −40° C. produces sulfamide (SO2(NH2)2) and oligomers thereof.
It has also been shown that FSO2NH2 is resistant to nucleophilic attack by ammonia at temperatures as high as −30° C. See R. Appel et al., “Uber die Umsetzung von Disulfurylfluorid, S2O5F2, mit Ammoniak und Diäthylamin,” Zeitschrift für anorganische und allgemeine Chemie 310 (1-2):90-93 (1961).
Conversely, a method of slowly adding NH3 to a stirred solution of SO2F2 to provide FSO2NH2 as the primary product has not been shown in the prior art.